This security update resolves vulnerabilities in Microsoft Windows. The vulnerabilities could allow elevation of privilege if an attacker logs on to an affected system and runs a specially crafted application or convinces a user to open a specially crafted file that invokes a vulnerable sandboxed application, allowing an attacker to escape the sandbox.

This security update is rated Importantfor all supported releases of Microsoft Windows except Windows 10, which is not affected. For more information, see the Affected Software section.

The security update addresses the vulnerabilities by correcting how Windows Object Manager handles object symbolic links created by a sandbox process, by preventing improper interaction with the registry by sandboxed applications, and by preventing improper interaction with the filesystem by sandboxed applications. For more information about the vulnerabilities, see the Vulnerability Information section.

The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

*The Updates Replaced column shows only the latest update in a chain of superseded updates. For a comprehensive list of updates replaced, go to the Microsoft Update Catalog, search for the update KB number, and then view update details (updates replaced information is on the Package Details tab).

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the August bulletin summary.

An elevation of privilege vulnerability exists in Windows Object Manager when it fails to properly validate and enforce impersonation levels. An attacker who successfully exploited this vulnerability could bypass impersonation-level security and gain elevated privileges on a targeted system.

In order to exploit this vulnerability, an attacker would have to log on to an affected system and run a specially crafted application. The vulnerability by itself does not allow arbitrary code execution; however, an attacker could use this vulnerability in conjunction with another vulnerability to effect arbitrary code execution. The update addresses the vulnerability by correcting how Windows Object Manager handles object symbolic links created by a sandbox process.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

Mitigating Factors

Workarounds

Windows Registry Elevation of Privilege Vulnerability - CVE-2015-2429

An elevation of privilege exists in Microsoft Windows when it improperly allows certain registry interactions from within vulnerable sandboxed applications. An attacker who successfully exploited this vulnerability could improperly interact with the registry and attempt to escape the application sandbox.

To exploit the vulnerability, an attacker would have to convince the user to open a specially crafted file that would invoke a vulnerable sandboxed application, resulting in a compromise of the sandbox. The attacker could then run programs with the privileges of the logged on user. The update addresses the vulnerability by preventing improper interaction with the registry by sandboxed applications.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

Workarounds

An elevation of privilege exists in Microsoft Windows when it improperly allows certain filesystem interactions from within vulnerable sandboxed applications. An attacker who successfully exploited this vulnerability could improperly interact with the filesystem and attempt to escape the application sandbox.

To exploit the vulnerability, an attacker would have to convince the user to open a specially crafted file that would invoke a vulnerable sandboxed application, allowing an attacker to escape the sandbox. The update addresses the vulnerability by preventing improper interaction with the filesystem by sandboxed applications.

Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was originally issued, Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers.

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